Modified methods of stellar magnetic field measurements

TL;DR

This paper introduces a modified stellar magnetic field measurement method using wavelet transforms to effectively reduce noise, validated through observations of various stars showing consistent results with existing techniques.

Contribution

The paper proposes a novel modification of standard magnetic field measurement methods by applying wavelet-based linear integral operators to suppress noise.

Findings

Effective noise suppression demonstrated with model line profiles.

Magnetic field measurements agree with established methods.

Validated on observations of multiple stars.

Abstract

The standard methods of the magnetic field measurement, based on an analysis of the relation between the Stokes $V$-parameter and the first derivative of the total line profile intensity, were modified by applying a linear integral operator $\hat{L}$ to the both sides of this relation. As the operator $\hat{L}$, the operator of the wavelet transform with DOG-wavelets is used. The key advantage of the proposed method is an effective suppression of the noise contribution to the line profile and the Stokes parameter $V$. The efficiency of the method has been studied using the model line profiles with various noise contributions. To test the proposed method, the spectropolarimetric observations of the A0-type star $\alpha^2\,$ CVn, young O-type star $\theta^1$ Ori C and A0 supergiant HD 92207 were used. The longitudinal magnetic field strengths for these stars calculated by our method appeared to be in a good agreement with those determined by other methods.